Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<queue>

using namespace std;

int main(){
	int h, w, ans = 0;
	cin >> h >> w;
	int inf = h * w + 100;
	vector<vector<char>> s(h + 2, vector<char>(w + 2, '#'));
	vector<vector<int>> c(h + 2, vector<int>(w + 2, inf));
	for(int i = 1; i <= h; i++){
		for(int j = 1; j <= w; j++){
			cin >> s[i][j];
			if(s[i][j] == '.') ans++;
		}
	}
	c[1][1] = 0;
	queue<pair<int, int>> q;
	q.push({1, 1});
	int dx[] = {0, 1, 0, -1}, dy[] = {-1, 0, 1, 0};
	while(!q.empty()){
		auto pa = q.front();
		int x = pa.second, y = pa.first;
		q.pop();
		for(int i = 0; i < 4; i++){
			int nx = x + dx[i], ny = y + dy[i], nc = c[y][x] + 1;
			if(s[ny][nx] != '#' && nc < c[ny][nx]){
				c[ny][nx] = nc;
				q.push({ny, nx});
			}
		}
	}
	ans -= c[h][w] + 1;
	cout << ((c[h][w] == inf)? -1 : ans) << endl;
	return 0;
}